Biosorption of copper, cadmium and lead by copper-resistant bacteria isolated from Mogpog River, Marinduque

Abstract

Heavy metal contaminants such as copper, cadmium and lead in water systems pose adverse health threats to humans. The use of copper-resistant bacteria as heavy-metal biosorbing agents may be able to substitute as a cheap but effective alternative to conventional heavy metal recovery methods. Isolation and selection of copper-resistant bacteria were carried out from collected water sample of Mogpog River in Marinduque. The water sample was also analyzed for Cu, Cd and Pb content for simulation purposes. The selected most copper-resistant bacterial isolate, Stenotrophomonas maltophilia, was exposed to 50 ppm of Cu, 10 ppm of Cd and 20 ppm of Pb in primary (single metal) and ternary (mixed metals) solutions of simulated Mogpog River water. Bacterial cells were separated from solutions after a defined contact time by centrifugation and the supernatants were analyzed using Atomic Absorption Spectrophotometry (AAS) to evaluate the ability of the bacteria to biosorb Cu, Cd and Pb. In primary solutions, biosorption profile was determined to be Cu>Pb>Cd; whereas in ternary solutions, the biosorption profile was Pb>Cu>Cd. Specific metal uptake (Q) showed that Cu and Cd removal was significantly reduced in ternary solutions while Pb removal was relatively less affected. Comparisons of biosorption of the three metals in primary solutions were all higher than biosorption in ternary solutions. Approximately 22 % of Cu, 24% of Cd and 42.75% of Pb were removed from primary solutions; 16% of Cu, 8% of Cd and 35% of Pb were removed from ternary simulated Mogpog River solutions by S. mahophilia.